Routine Use of Gemtuzumab Ozogamicin in 7+3-Based Inductions for All 'Non-Adverse' Risk AML

Introduction: The addition of gemtuzumab ozogamicin (GO) to 7+3 chemotherapy for newly diagnosed acute myeloid leukemia (AML) has been shown to significantly improve event-free survival (EFS) for cytogenetically favorable-risk AML, with marginal benefit for intermediate-risk AML, and no benefit for cytogenetically adverse-risk AML. Of note, with the exception of mutated FLT3-ITD, little is known about the impact of GO in ELN 2017-defined genotypically adverse-risk AML, and a recent randomized trial found no EFS benefit for 7+3+GO in patients (pts) with genotypically favorable-risk, NPM1-mutated AML. Since 2017, our institution incorporated GO into 7+3-based inductions for all "non-adverse" risk AML pts, as defined by wild-type FLT3 and no abnormalities on rapid FISH analysis for del(5q)/monosomy 5, del(7q)/monosomy 7, and del(20q). We report our experience treating all pts with "non-adverse" risk AML-as defined by this algorithm-with 7+3+GO. Methods: An institutional database was queried in order to identify all pts ≥18 years old who received 7+3-based chemotherapy for newly diagnosed AML between 2017 and 2020; pts who received the FDA-approved fractionated dose of GO were included in the analysis. Data collection included demographic variables, karyotype/FISH, targeted PCR analyses, and multigene NGS panels for AML-related mutations including, but not limited to, mutations in FLT3, NPM1, CEBPA, TP53, RUNX1, and ASXL1. Outcome data included response to induction, relapse, and death, as well as hematopoietic cell transplant (HCT) rates, conditioning regimens, and post-transplant complications. Results: Between January 2017 and July 2020, 96 pts received 7+3-based induction at our institution. Of these, 29 (30%) received 7+3 in combination with GO. Median age at diagnosis was 46 years (range 23-66), with 17 (59%) males. Sixteen (55%) pts had ELN favorable-risk AML (5 [31%] by cytogenetics and 11 [69%] by genotype), 6 (21%) pts had ELN intermediate-risk AML, and 7 (24%) pts had ELN adverse-risk AML (4 [57%] by cytogenetics and 3 [43%] by genotype). Median time from diagnosis to start of induction was 4 days (range 0-43). For cytogenetically adverse-risk pts, median time from diagnostic bone marrow biopsy to receipt of adverse karyotype results was 8 days (7-14). Median time from start of induction to receipt of multigene NGS results for all pts was 15 days (3-32). Overall, 22 (76%) pts achieved remission. All genotypically adverse-risk pts (1 with mutated TP53 and 2 with mutated RUNX1) were refractory to induction, while 3 of 4 (75%) cytogenetically adverse-risk pts (1 with t(6;9), 1 with monosomy 7, and 2 with 11q23 abnormalities) achieved remission. Eight of the 29 (28%) pts proceeded to HCT, including 4 adverse-risk pts. Of the adverse-risk pts, all received myeloablative conditioning prior to HCT and 3 (75%) developed veno-occlusive disease (VOD), with 2 (50%) requiring defibrotide therapy. In favorable/intermediate-risk pts, 4 (18%) proceeded to HCT (2 intermediate-risk pts in first remission and 2 favorable-risk pts in second remission). Of these, 2 (50%) received myeloablative conditioning and 1 (25%) developed VOD. At last follow-up, 23 of 29 pts (79%) remained alive, with a median overall survival not reached (range 1-29 months) and a median EFS of 20 months (9-31). The percentage of ELN favorable-, intermediate-, and adverse-risk pts who remained event-free at last follow-up was 75%, 33%, and 43%, respectively. Discussion: This single-center, retrospective cohort describes the outcomes of pts with "non-adverse" risk AML who received induction chemotherapy with 7+3+GO according to a pre-defined algorithm. Using this algorithm, 30% of all pts receiving 7+3-based inductions received GO. Of these, nearly 25% were ultimately found to have adverse-risk AML as defined by ELN 2017 criteria, largely driven by long turn-around times for karyotyping and NGS multigene panel results. No patient with genotypically adverse-risk AML by ELN criteria responded to induction chemotherapy, and 75% of cytogenetically adverse-risk pts who proceeded to HCT developed VOD. Routine use of 7+3+GO induction outside of the context of cytogenetically favorable-risk AML remains controversial, and further study is needed to define the role of GO, particularly for pts with ELN genotypically adverse-risk AML. Table Disclosures Gotlib: Blueprint Medicines Corporation: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees, Other: Chair of the Response Adjudication Committee and Research Funding, Research Funding; Deciphera: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees, Other: co-chair of the Study Steering Committee and Research Funding. Liedtke:Jazz Pharmaceuticals: Membership on an entity's Board of Directors or advisory committees; Janssen: Membership on an entity's Board of Directors or advisory committees; Pfizer: Honoraria; GSK: Membership on an entity's Board of Directors or advisory committees; Adaptive: Membership on an entity's Board of Directors or advisory committees; Caelum: Membership on an entity's Board of Directors or advisory committees; Celgene: Membership on an entity's Board of Directors or advisory committees. Muffly:Adaptive: Research Funding; Amgen: Consultancy; Servier: Research Funding. Mannis:AbbVie, Agios, Bristol-Myers Squibb, Genentech: Consultancy; Glycomimetics, Forty Seven, Inc, Jazz Pharmaceuticals: Research Funding.